her, could only be distinguished by a minute comparison
after being captured.

The last six cases of mimicry are especially instructive, because they
seem to indicate one of the processes by which dimorphic forms have been
produced. When, as in these cases, one sex differs much from the other,
and varies greatly itself, it may happen that occasionally individual
variations will occur having a distant resemblance to groups which are
the objects of mimicry, and which it is therefore advantageous to
resemble. Such a variety will have a better chance of preservation; the
individuals possessing it will be multiplied; and their accidental
likeness to the favoured group will be rendered permanent by hereditary
transmission, and, each successive variation which increases the
resemblance being preserved, and all variations departing from the
favoured type having less chance of preservation, there will in time
result those singular cases of two or more isolated and fixed forms,
bound together by that intimate relationship which constitutes them the
sexes of a single species. The reason why the females are more subject
to this kind of modification than the males is, probably, that their
slower flight, when laden with eggs, and their exposure to attack while
in the act of depositing their eggs upon leaves, render it especially
advantageous for them to have some additional protection. This they at
once obtain by acquiring a resemblance to other species which, from
whatever cause, enjoy a comparative immunity from persecution.

_Concluding remarks on Variation in Lepidoptera._

This summary of the more interesting phenomena of variation presented by
the eastern Papilionidae is, I think, sufficient to substantiate my
position, that the Lepidoptera are a group that offer especial
facilities for such inquiries; and it will also show that they have
undergone an amount of special adaptive modification rarely equalled
among the more highly organized animals. And, among the Lepidoptera, the
great and pre-eminently tropical families of Papilionidae and Danaidae
seem to be those in which complicated adaptations to the surrounding
organic and inorganic universe have been most completely developed,
offering in this respect a striking analogy to the equally
extraordinary, though totally different, adaptations which present
themselves in the Orchideae, the only family of plants in which mimicry
of other organisms appears to play any important